Preparation of 2-phenyl-allyl-chloride



United States Patent 3,361,835 PREPARATION OF Z-PHENYL-ALLYL-CIHORIDE Willis C. Keith, Lansing, and Robert P. Zmitrovis, Park Forest, 111., assignors to Sinclair Research, Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed May 13, 1965, Ser. No. 455,607 2 Claims. (Cl. 260-651) This application is a continuation-in-part of application Ser. No. 301, 168, filed Aug. 9, 1963, and now abandoned, which latter application is a continuation-in-part of application Ser. No. 138,299, filed Sept. 15, 1961, and now abandoned.

This invention is a method for the chlorination of a-methyl styrene to produce 2-phenyl-allyl chloride in good yields. The 2-phenyl-allyl chloride is a valuable intermediate for the preparation of synthetic resins and oil additives and may easily be converted to the cone sponding alcohol, ester, and numerous other derivatives such as 1-cyano-2-phenyl-propene-1.

It has been found that u-methyl styrene may be chlorinated in the vapor phase to produce 2-phenyl-allyl chloride as well as other products and that the yield of the allyl chloride is maximized by the use of certain select elevated temperatures and contact times. In vapor phase chlorination, the following reactions may take place:

phenyl-propane-l The process is operable to produce the allyl chloride at temperatures above the boiling point (165 C.) of the a-methyl styrene and below its decomposition temperature. However, it has been found that the product distribution is temperature and contact time dependent and that high selective yields of Z-phenyl-allyl-chloride can be obtained by operating at a temperature of about 475 to 550 C. and at an unusually low contact time of about 0.01 to 0.1 second. Use of a contact time much above 0.1 second significantly reduces the selectivity to Z-phenyl-allyl chloride. Likewise, operating at temperatures below about 475 F. at these low contact times fails to provide the desired selectivity to 2-phenyl-allyl chloride.

The vapor phase reaction can be carried out in the 3,361,835 Patented Jan. 2, 1968 absence of a catalyst and a bed of inert solids may be provided to distribute the reactants and moderate the heating to prevent hot spots. The reaction is highly exothermic and good dissipation of the heat is advisable. The inert solids may be disposed as a fluidized bed. A fixed bed of solids may also be used for the reaction and the reactants may be passed through a fixed bed of inerts for preheating or cooling. Low pressure steam may be employed to quench the reaction to avoid substantial polymer formation but a water quench is preferred.

The feed to the process of this invention is u-methyl styrene which may contain an innocuous substituent such as alkyl of 1-5 carbon atoms, phenyl, halide of 9 to 53 atomic number, etc. The feed advantageously is a hydrocarbon.

The molecular chloride gas may be fed alone to the reaction but preferably an inert diluent, advantageously nitrogen or steam, is fed along with the chlorine and, if desired, along with the a-methyl-styrene as well. About 0.5 to 20 moles of a-methyl-styrene may be fed to the reaction per mole of chlorine, preferably 2 to 5 moles of hydrocarbon per mole of molecular chlorine gas. About 0.5 to 20 or more volumes of diluent may, if desired, be employed for each combined volume of chlorine and m-methyl styrene. As aforementioned, the time of contact of the reactants can vary from about 0.01 to 0.1 second, preferably about 0.02 to 0.08 second. The products of the reaction may be easily separated for recovery of the 2-phenyl-allyl chloride by fractional condensation or by total condensation and distillation.

The process of the invention will be better understood by reference to the following examples in which alphamethyl-styrene and chlorine were reacted in vapor phase.

Example I The reactor used was a small fluidized bed reactor which provided good control of reaction temperature. Three separately heated furnaces were used to provide good temperature control in a preheating, a reaction, and a quenching zone. The preheating zone was provided with a fixed bed of inerts, a porous dispersion plate between it and the reaction zone, and an entry for diluent gas and hydrocarbon reactant. The reaction zone was provided with silicon carbide particles in a fluidizable size and with a capillary tube for entry of chlorine and diluent just above the dispersion plate. The exit of the quenching zone was provided with an entry for low-pressure steam and with a tube which leads to a condenser.

The reactor was purged with diluent while being heated to the desired temperatures. The a-methyl styrene, plus a small amount of steam diluent, entered the fixed bed of inerts at the desired rate by means of a Milton Roy minipump. The feed was vaporized and preheated to reaction temperature and passed through the porous plate to the reaction zone. The molecular chlorine gas, also diluted with steam, was introduced at a constant rate by means of a low pressure regulator-flowmeter assembly, just above the dispersion plate, through the capillary tube, and the reaction mixture passed through the fluidized zone, to the quenching zone. The low pressure steam (about 100 C.) was turned on prior to the addition of chlorine, no attempt being made to adjust the steam other than to insure an ample quantity of water to quench the reaction. The reaction temperature was easily adjusted by regulating the furnaces for the pre-heat and reaction zone. The temperature was controlled within :5 C. of the desired temperature. After the reactor was lined out the product was collected and worked up. The workup consisted of separating the organic phase from the water, followed by an additional washing with water to remove traces of HCl. The product was dried over Ca(SO and fractionated at a (1) Unreacted u-methylstyrene (2) V Mono-chlorides stainless steel valve with prolonged stem was welded to the exit of the reactor and the valve-was connected to was attached to the quench zone to introduce the quench,

gigggfi 5 'water. The preheaters, reaction zone and initialpart of the i I quench zone were all submerged in a well-stirred salt Fractions and 3 were analyzed for Percent Chlorillfi bath kept at constant temperature. The reaction product and allyl-chloride content as indicated by etherification was l d to room temperature d ll d i a odrlurrlberother H1118 3 and were conductfid which uct receiver. The liquid product was separated into an used nitrogen as the diluent in the reaction. The results organic layer d n aqueous layer. The aqueous layer are tabulated below: (about 3500-4000 ml.) was recycled as quench water (about 27 ml./min.). The vaporous reaction product Example No. in form of obnoxious white fumes was passed successively through a wash bottle containing water through three 1 2 3 4 large traps in Dry-Ice, the last one containing a Demlstor pad to increase the surface, and through two towers lg a z i n Temrc.) 25g 3 g 3 4 containing each approximatelg 22% g; activae l ca non lme Th exit nitrogen was saturate wit water an i 8 V0 111116 gggggfifll 1. 32 1. 02 313 measured. A 1few ttilheck tests showectl that th sJ organic laygr r: V in the traps ad e same composl 1011 as e mam pro i 1ii%Z a ii1 -%Sr;i ah (i 33 uct. It was therefore assumed that this is also the case 1Iz'dichmm'zpheuyl'pmpane-- 67 no for the vapors adsorbed in the carbon tower. A'total of approximately 2-3% ,of product was collected in traps The effect of temperature on product distribution is d towers clearly illustrated by the above results. Very little change A premn f approximately 200 ml. m-methyl styrene in product distribution takes place in going from 250 C. f d was d to get h system into equilibria, followed to 330 C. but an abrupt change in product distribution y a f 210420 f ed The separatedrhazy aquatakes place as the temperature exceeds 330 The yield ous layer was heated to 40 50o C" Sodium chlm of z pher.lyl'auyl'chlonde mcreases r.aP1d.1y as t ride was added and the layer cooled to room temperature. perature increases. A plot of product dlstribution against An additional product was recovered in this g gg g i fi g j izz iigi gi g g g and ner. A standard amount of 8 g. was added to the total W p e r weight due to unrecoverable losses in the quench water. Example H The reaction product was then dried by shaking with V The fcllgwing chlorinations of aqnethyl tyrene were 35 Drierite. The chlorinated a-methyl styrene reaction PI'Odmade to illustrate that the high temperatures and shorter was analyled y gas chromatographycontact times of the invention provide surprisingly high Data from such tests are reported in the followmg selectivity of 2-phenyl-allyl chloride. In these reactions table:

TABLE Run No.

Reaction Temp. C.) 350 421 500 496 503 542 500 500 Contact Time (sec.) 0.05 0.05 0.1 0.076 0 025 0. 05 0. 01 0.005 Mole ratlo hydrocarbon to chlorine 3.3 3. 3 4. 0 3.3 3. 3 3. 3 3. 3 3. 3 Volume ratio N2 diluent to reactants 3. 0 6. 2 3. 0 3.0 3. 1 8. 1 3.0 3.0 Pressure, p.s.i.g 40 40 40 40 40 60 60 Product, wt. percent:

2-phenyl allyl chloride 15. 4 23. 3 20. 9 28. 4 30. 9 27. 3 27. 9 23. 4 1-chloro-2-phenyl propene-l 5. 6 2. 7 0. 9 0. 5 0. 6 0. 24 0. 7 3. 1 fl-Chloro-fi-methyl styrene 1. 0 0. 5 0.2 0.2 0. 1 Divhlmw'd 1s. 4 10. 9 s. 4 4. 9 6.0 6. 4 9. 0 14. 4 Weight ratio of Q-phenyl allyl chloride to 1-chloro-2-phenyl propene-l and B-chloro-fl-rnethyl styrene 2.3/1 7.3/1 23/1 41/1 39/1 80/1 40/1 7.61 Weight ratio of Z-phenyl allyl chloride to dichlorides 0.84/1 2.1/1 2. 5/1 5. 8/1 5. 1/1 4. 3/1 3. 1/1 1. 6/1

u-methyl styrene was pumped into a preheating coil. The data of the table illustrates the importance of the Chlorine from a cylinder was dried and fed into another 0 reaction temperatures and contact times in the present preheating coil. The nitrogen used as diluent was fed invention insofar as obtaining high selective yields of in two equal streams into the two preheating coils. Two 2-phenyl-allyl chloride are concerned. Runs 1 and 2 show thermowells at the end of the preheaters allowed for that the contact times of the present invention with lower measuring the temperature of the two feed streams which temperature give considerable by-product formation. Run had salt bath temperature in all runs. The feed lines were 8 shows that use of a contact time less than about 0.01 connected to the reactor through a short piece of capillary even at the high temperatures of the invention also gives tubing to avoid back-mixing. The reaction zone consisted considerable by-product formation. Runs 3 to 7 represent of a tube having a concentric thermowell. The reactor the process of the present invention and illustrate the volume was 4.65 ml. and the difference between the surprisingly selectivity to 2-phenyl-allyl chloride provided. diameters of the reactor tube (ID) and the thermowell We claim: (OD) was 1.2 mm. At the end of one feedline and at the 1. The method of preparing 2-phenyl-allyl chloride upper end of the reactor a 1 mm. ID capillary lead to a which comprises reacting in the vapor phase a-methyl pressure gauge. A small bleed of nitrogen was used to styrene with chlorine at a temperature of about 475 C. avoid condensation of product in these capillaries. The to 550 C. and for a contact time of about 0.01 to Q1 second.

preheaters and reactor were made of lnconel. A small 5 2. The method of claim 1 wherein a molar ratio of OTHER REFERENCES alpha-methyl styrene to chlorine of about 2 to 5/1 is fed Hatch et a1: Amer Chem VOL 76, 1954 pp. to the reaction zone.

. Tifieneau: Annales de Chimie et de Physique, 8

References Clted 5 vol. 10, 1907, p. 166. UNITED STATES PATENTS 2,130,084 9/1938 Groll et a1 260651 X LEON ZITVER Prlma'y Examme 2,981,758 4/1961 Hoffenberg 260651 X H. MARS, K. V. ROCKEY, Assistant Examinelis'.

3,100,232 8/1963 Keith et a1. 260-651 

1. THE METHOD OF PREPARING 2-PHENYL-ALLYL CHLORIDE WHICH COMPRISES REACTING IN THE VAPOR PHASE A-METHYL STYRENE WITH CHLORINE AT A TEMPERATURE OF ABOUT 475*C. TO 550*C. AND FOR A CONTACT TIME OF ABOUT 0.01 TO 0.1 SECOND. 